diff --git a/src/syncio.c b/src/syncio.c
index 8810a842..ac2a4a37 100644
--- a/src/syncio.c
+++ b/src/syncio.c
@@ -139,6 +139,7 @@ ssize_t syncReadLine(int fd, char *ptr, ssize_t size, long long timeout) {
             *ptr = '\0';
             nread++;
         }
+        size--;
     }
     return nread;
 }